EasyPrint

A secure PDF print-job submission system. Users upload PDFs and receive a QR code + PIN; shop staff scan the QR code, verify the PIN, and trigger the print. Jobs expire after 10 minutes.

I built it around one constraint: a customer should be able to print at a shop without handing over their file by email, USB, or a logged-in account — just a QR code and a PIN that dies in ten minutes.

Tech Stack

Layer	Tech
Backend	Python 3.11, FastAPI, Uvicorn
Frontend	React 19, React Router, Vite
QR	qrcode.react (generate), ZXing (scan)
Print	CUPS (lp) / Windows, with stub fallback

User Flows

Customer (User page → /user)

1. Upload a PDF, choose pages and copies.
2. Receive a QR code containing the job_id and a 6-digit PIN.
3. Share the QR code with the print shop.

Shop Staff (Shop page → /shop)

1. Scan the customer's QR code with the device camera.
2. See job details (pages, copies, expiry).
3. Enter the PIN to authorise and trigger the print.

API Endpoints

Method	Path	Description
POST	/upload	Upload PDF, returns job_id+PIN
GET	/job/{job_id}	Get job details
POST	/print/{job_id}?pin=	Authorise and print
POST	/shop/session	Create a shop session
GET	/shop/session/{session_id}	Poll session for a job

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Running with Docker (recommended)

Requires Docker Desktop.

docker compose up --build

Stop everything:

docker compose down

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Running Locally (without Docker)

Backend

cd backend
python -m venv venv

# Windows
venv\Scripts\activate
# macOS / Linux
source venv/bin/activate

pip install -r requirements.txt
uvicorn main:app --reload

Backend runs at http://localhost:8000.

Frontend

cd frontend/secure-print-ui
npm install
npm run dev

Frontend runs at http://localhost:5173.

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Design notes & limitations

These are prototype boundaries I chose on purpose:

• In-memory job store. Jobs and shop sessions live in process memory, so a restart clears them and it runs as a single instance. A persistent store (Redis / a database) is the next step for multi-instance use.
• Short-lived, single-use PINs. A 6-digit PIN (drawn from secrets) paired with a 10-minute expiry and one-shot printing limits the exposure window. Per-job attempt throttling is the obvious next hardening step.
• Printing adapts to its environment. The backend uses CUPS (lp) where available, falls back to the Windows print verb, and otherwise logs a stub — so the full flow is demoable without a physical printer.